Gepirone and its salts are antidepressant and anxiolytic agents. They are typically used to treat depression, dysthymia, impulse disorders, panic attacks and the like. Gepirone has a short half-life when orally administered in immediate-release formulations. Its time to maximum drug concentration in the bloodstream (Tmax) is about 1 hour and its T-50 (i.e. time until 50% of the drug has been released under controlled in vitro conditions) is about 2.5.degree.3 hours. Because of its rapid metabolism, gepirone has been administered in the past in several small dosages--e.g., 5 to 10 rag. doses, 2 to 3 times per day. This multiple dosing scheme can lead to compliance problems. Failure to take the second or third dose results in unacceptably low plasma levels of gepirone.
Also, studies indicate that, for 15 to 20 hours after administration, oral immediate release gepirone formulations can yield significant variations in human plasma concentrations.
Gepirone has the names:
(1) 4,4-dimethyl-1-[4-[4-(2-pyrimidinyl)-1-piperazinyl]butyl]-2,6-piperidinedi one, and PA1 (2) 3,3-dimethyl-1-[4-[4-(2-pyrimidinyl)-1-piperazinyl]butyl]-glutarimide.
It can be effectively administered using its hydrochloride salt, gepirone hydrochloride (gepirone HCl). The preparation of gepirone hydrochloride is described in Example 7 of U.S. Pat. No. 4,423,049 to D. L. Temple et al.
Gepirone's principal metabolite is 1-(2-pyrimidinyl)piperazine (1-PP). The release of 1-PP is believed to be responsible for adverse side effects. Such side effects include dizziness, nausea, headache and drowsiness.